Science — AI-generated practice question

Control of stomata by guard cells:
Guard cells surround each stomatal pore. When water flows into the guard cells, they swell and become turgid, causing the stomatal pore to open. When the guard cells lose water and shrink, the pore closes.

Why stomata close during daylight:
Although stomata need to remain open during the day for CO₂ intake for photosynthesis, the plant may close them even in daylight to prevent excessive loss of water through transpiration. Since large amounts of water can be lost through stomata, the plant closes the pores when it does not need CO₂, balancing water conservation with gaseous exchange.

Source: Chapter 5, Section 5.2.1 — Autotrophic Nutrition

---

• The examiner expects two clear parts: mechanism (guard cell swelling/shrinking) and reason for closing in daylight (water loss/conservation).
• Key terms to use: turgid, guard cells, stomatal pore, water loss, transpiration, CO₂.
• Don't over-explain photosynthesis — focus on the stomata function as stated in the passage.
• The passage explicitly states: "since large amounts of water can also be lost through these stomata, the plant closes these pores when it does not need carbon dioxide" — mirror this language in your answer.